1. Field of the Invention
The present invention relates to a method for driving an opening/closing member to open and close an opening. In more particular, the present invention relates to an opening/closing member driving method which is suited to re-initialize (re-recognize) the initial position (original position) of an opening/closing member.
2. Related Art
Conventionally, as a device for opening and closing an opening part using an opening/closing member, there are proposed various kinds of devices such as a damper device for a refrigerator which is installed within a cool air blow-out portion of the refrigerator or a cool air duct thereof. For example, as shown in FIGS. 17 and 18, in a motor type damper device 101 which is a single type damper device for a refrigerator including a single opening part, there is employed a structure in which a baffle 103 and a drive mechanism part 104 are disposed in a mutually opposed manner with a rotation support shaft 102 between them (see Unexamined Japanese Patent Publication Hei. 6-109354). In operation, in the motor type damper device 101, the rotation torque of a motor is transmitted to the rotation support shaft 102 and thus the baffle 103 is rotated about the rotation support shaft 102, thereby opening and closing an opening part 106 which is formed in a frame 105.
By the way, when such single type or motor type damper device 101 including a single opening/closing member is installed in a refrigerator, the motor type damper device 101 is controlled in such a manner that the baffle 103 can be set in a full opened position and in a full closed position. However, if the baffle 103 is set in the full opened position, then a cool air cooled by a cooling device is smoothly flown into the refrigerator but too much, so that the temperature of the interior portion of the refrigerator is lowered too much. For example, in a refrigerator including a compartment which is referred to as a chilled compartment, the interior of the chilled compartment must be severely controlled to a predetermined temperature. In this case, the baffle 3 is controlled in such a manner that it can also be set at an intermediate position between the full opened and closed positions thereof. That is, the baffle 3 can be held respectively at the full closed position, full opened position and intermediate position. By the way, in some specifications, there is employed a structure such that the baffle 103 is not driven up to the full opened position thereof but is driven only up to the intermediate position thereof.
Also, in the damper devices for use in a refrigerator and the like including the above-mentioned motor type damper device 101, when the opening part 106 is closed by the baffle 103, an cool air or the like must be shut out forwardly. For this purpose, a lead switch or the like is used to detect the position of the baffle 103.
Also, recently, there has been increasing a refrigerator of a type that the interior portion of the refrigerator is divided into two or three or more compartments and all of the compartments are controlled in temperature. In particular, in the refrigerator of this type, there are used a plurality of motor type damper devices 101 each including a single opening part 106 shown in FIGS. 17 and 18, or there is used a double damper device 111 including two openings 106 as shown in FIG. 19. In the double damper device 111, there are formed two openings 106 and 106 in the frame 105 and a drive mechanism part 104 such as a motor and the like is disposed on the lower side of the back surface of the frame 105. And, there are disposed two baffles 103 as shown in FIGS. 17 and 18, while the two baffles 103 are driven by a single synchronous motor (not shown) or a stepping motor (not shown) or the like included in the drive mechanism part 104 to thereby open and close the two openings 106 and 106.
Referring to the operations of the two baffles 103 and 103, there are arranged four modes: that is, a first mode in which both of the baffles 103 and 103 are held at their opened positions (opened-opened mode); a second mode in which both of the baffles 103 and 103 are held at their closed positions (closed-closed mode); a third mode in which one baffle 103 is held at its opened position and the other is held at its closed position (opened-closed mode); and, a fourth mode in which one baffle 103 is held at its closed position and the other is held at its opened position (closed-opened mode). By the way, in the present double damper device 111, by driving the drive motor by a predetermined amount, the two baffles 103 can be driven sequentially in the order of the closed-closed mode, opened-closed mode, opened-opened mode, and closed-closed mode.
In the present double damper device 111, since the two baffles 103 and 103 are controlled in temperature while they are positioned and held in the four modes, even when the two baffles 103 are positioned and held only at the two positions, that is, the full opened positions and the full closed positions, as the whole of the refrigerator, the temperature of the refrigerator can be controlled more finely than the single type damper device. Thanks to this, as measures to prevent the interior portion of the refrigerator from being cooled too much, there is no need to position and held the two baffles 103 at their respective intermediate positions.
However, in both of the above-mentioned conventional motor type damper device using a single damper, that is, a single opening/closing member and double damper device 111, there is required a detect mechanism for detecting the position(s) of the baffle(s) 103, which results in the complicated and expensive damper device(s). In view of this, to remove the position detection mechanism from the damper device is sufficiently effective in improving the technological performance of the damper device as well as in reducing the cost of the damper device.
For example, the single damper device can be driven by a stepping motor in such a manner that, in accordance with the number of pulses to be applied to the stepping motor, the device is able to take three positions, namely, a full opened position, a full closed position and an intermediate position; and, the double damper device can be similarly driven by a stepping motor in such a manner that, in accordance with combinations of the pulse number and cam mechanism, the device is able to take four modes, that is, an opened-opened mode, an opened-closed mode, a closed-closed mode, and a closed-opened mode.
However, because such damper devices do not include any position detect mechanism, even if the baffles are shifted in position for some reason or other, the shifted position thereof cannot be detected. For this reason, there arises the need to recognize or initialize the original positions of the baffles with predetermined frequency. In such initialization, in order to move the baffle to the original position thereof forwardly, the baffle is driven with the number of pulses larger than the full step number and is locked mechanically, thereby initializing the initial state of the baffle.
For example, in the motor type or single type damper device, even if the baffle is held at the intermediate position, in the initialization, in order to move the baffle to the original position forwardly, the baffle is driven to in the original position direction with the number of steps larger than the full step number.
Therefore, still after the baffle is butted against the original position, the stepping motor is driven on, so that the baffle can keep its locking state in which it is butted against the opening. However, during such locking operation, not only there can be produced noise but also an abnormal load can be applied onto the gear of the motor.
In the damper device which does not include a position detection mechanism, the above-mentioned initialization is indispensable. However, the noise degrades the commercial value of the damper device and the abnormal load shortens the life of the damper device.